TOKYO (AFP) - Chinese ships sailed into Tokyo-controlled waters on Tuesday as Beijing celebrated its National Day and as Japan and the United States prepare for talks on their defence pact.
Four vessels from the Chinese coastguard entered the territorial waters of the Senkaku islands at around 9am (8am Singapore time), the Japanese coastguard said.
China calls the islands the Diaoyus and says they belong to Beijing.
It came as US Secretary of Defense Chuck Hagel and Secretary of State John Kelly prepare to head to Tokyo for a meeting on Thursday with Japanese counterparts Itsunori Onodera and Fumio Kishida.
Japan's hawkish Prime Minister Shinzo Abe wants Tokyo to play a more self-confident role on the world stage and for its military to shoulder more of the burden of the defence pact with Washington.
The so-called "2+2" meeting will discuss operational arrangements for the Tokyo-Washington alliance, which were last amended in 1997, officials have said.
The latest incident also comes on the anniversary of the founding of the People's Republic of China in 1949, a day marked by a public holiday throughout the country.
In recent months there have been fewer incidents than in the opening stages of the row over the islands, which erupted violently in September last year.
However, China has apparently loosely tied the sallies to significant events, either diplomatic or domestic.
Observers say Beijing wants to create a "new normal" by demonstrating that Japan no longer has effective control over the islands. It hopes that could force Tokyo to the negotiating table over their future - something Japan has repeatedly ruled out.
Tokyo is not prepared even to acknowledge formally the existence of any dispute.
Asia-watchers say the tense stand-off could erupt into a limited armed conflict, with some warning that it may even draw the United States in.
So far there has been little diplomatic headway on finding a solution, although both sides have made qualified offers of talks.
The long-running dispute over the ownership of the islands flared into a bitter row about a year ago when Tokyo nationalised part of the chain.